As an enzyme for acting on a protein (polypeptide) so as to specifically cleave the carboxyl side of a glutamic acid (Glu) residue, V8 protease derived from Staphylococcus aureus V8 strain is known (Gabriel R. Drapeau et al., J. Biol. Chem. 247, 20, 6720-6726 (1972)). This enzyme is classified as a serine protease. C. Carmona et al. (Nucl. Acids Res., 15, 6757 (1987)) cloned a DNA sequence for encoding this enzyme.
A similar enzyme, acidic amino acid specific endopeptidase derived from Streptomyces griseus, which is an actinomyces, is also known (Norio Yoshida et al., J. Biochem. 104, 3, 451-456 (1988)). Recently, I. Svendsen et al. reported an amino acid sequence of the acidic amino acid specific endopeptidase purified from Streptomyces griseus (FEBS LETTERS 292 165-167 (1991)). Furthermore, glutamic acid specific endopeptidase derived from Bacillus subtilis is also known (Takuro Niidome et al., J. Biochem. 108, 965-970 (1990)). With respect to some of these proteases, the characteristics thereof have been studied and inhibitors against them are known (K. Nagata et al., J. Biochem. 110, 859-862 (1991) and T. Komiyama, J. Biol. Chem. 266, 17, 10727-10730 (1991)).
The aforementioned enzymes are useful for specifically cleaving a protein at the aforementioned site for the purpose of structural analysis of the protein; for obtaining an objective protein through cleavage of a fusion protein in the case where the objective protein is desired to be produced as the fusion protein by a genetic recombination technique and the like. In the latter case, for example, after producing the objective protein by coupling with another protein through a Glu residue, the resultant is subjected to cleavage with one of the enzymes. Thus, the objective protein can be separated. Accordingly, there is a demand for a protease having such an enzymatic activity other than the above-mentioned enzymes.